Cellulose products and process for making same



3,051,693 CELLULOSE PRODUCTS AND PROCESS FOR MAKING SAME Lee H. Elizer,Glen C. Glasscock, and John M. Seitz, Keokuk, Iowa, assignors to TheHuhinger Company, Keokulr, Iowa, a corporation of Iowa No Drawing. FiledJune 22, 1959, Ser. No. 821,675 23 Claims. (Cl. 260-212) This inventionrelates to new substituted cellulose derivatives and to processes formaking them.

The object of this invention is to provide new cationic, nitrogenatedcellulose derivatives.

Another object is to provide new methods for making said cationic,nitrogenated cellulose derivatives.

Still another object is to provide cationic, nitrogenated cellulosederivatives which possess marked afiinity for acid or wool-type dyes aswell as for other anionic conditioning or coating compositions, such asanionic resins and starches.

Other objects and advantages will become obvious from the followingdescription.

We have discovered that when cellulose, both natural and regenerated,such as cellophane, viscose rayon and the like, and cellulosederivatives, such as cellulose esters of fatty acids, and celluloseXanthate, are treated with an aqueous alkaline solution of cyanamide,they react to form new cationic nitrogenated products. Thesenitrogenated products, when treated with an acid, form stable cationicacid salts. The aqueous alkaline cyanamide solution can be prepared bydissolving cyanamide in a solution of an" alkali or alkaline earth metalbase or by dissolving an alkali or alkaline earth metal cyanamide inwater.

It will be understood that both in the specification and claims, thealkali metal and alkaline earth metal cyanamides include both thecompletely metallated cyanamide, such as CaNCN and Na NCN, and the metalhydrogen cyanamides, such as Ca(I-INCN) or NaHNCN.

Conditions essential for the desired reaction include an aqueous solventmedium and an alkaline reaction mixture. For appreciable nitrogen add-onand cationicity, the pH should be above 7, preferably at least about pH8.5 and preferably in the range of about to 12.5.

Reaction of the cellulose or cellulose derivative with the cyanamideoccurs at any temperature from the freezing to the boiling points of thereaction mixture. In general, reaction rate increases with increasingtemperature. Thus for very rapid nitrogenation, the temperature can beelevated, as, for example to about 200 F. However, digestion periods atsuch elevated temperatures are desirably shortened since, after a pointof maximum substitution at the given reagent concentration,decomposition or rearrangement sets in, as demonstrated by some nitrogenloss.

Other conditions, such as the ratio of the cyanamide to the cellulosicmaterial, the concentration of cyanamide dissolved in the reactionmixture, and the period of reaction, are not critical, although they doinfluence the extent of nitrogen substitution. For example, higherratios of total cyanamide to the cellulosic material tend to increasethe degree of substitution.

The precise nature of the reaction mechanism or of the substituentnitrogen-containing radicals is not yet completely understood. It islikely that reactive hydroxyl groups of the cellulose or cellulose esterparticipate in the reaction. In the case of cellulose esters, such ascellulose acetate, such free hydroxyl groups can be initially present orcan be produced by hydrolysis under the alkaline conditions of thereaction. When an alkali metal or alkaline earth metal cyanamide isdissolved in water 3,051,698 Patented Aug. 28, 1962 or when cyanamide isdissolved in an aqueous alkaline solution, the (HNCN)- ion is formed. Weconsider it probable that this ion is the reactive agent. It will beunderstood, however, that the invention is not to be restricted by theforegoing hypothesis.

As aforementioned, the aqueous cyanamide treatment is effective withcellulose in its natural or regenerated forms, with fatty acid esters ofcellulose, such as cellulose acetate, cellulose propionate, cellulosebutyrate and mixed esters, such as cellulose acetate propionate andcellulose acetate butyrate, and with cellulose xanthate. The cellulosicmaterial can be treated in anydesired physical form, as, for example, inthe form of a fiber, pulp, or granule slurry, woven cloth, paper sheets,or plastic films. The cellulose can be derived from any source such aswood, cotton, straw, pith, and the like. Cellulose xanthate can betreated in solution.

The nitrogen-containing reagent, as previously stated, is cyanamidedissolved in an aqueous alkaline solution, preferably of an alkali metalor alkaline earth metal base, such as sodium, potassium, lithium,calcium, barium or strontium hydroxide, or their basic salts, or anaqueous solution of-an alkali metal or alkaline earth metal cyanamide,such as sodium, potassium or calcium cyanamide. It is ordinarily notnecessary to add a base to a solution of the cyanamide salt sincesolutions of such salts in water are generally sufficiently alkaline. Anaqueous solution of calcium cyanamide, for example, generally has a pHin the range of about 10.5 to 11.9. An alkali metal or alkaline earthmetal'cyanamide hydrolyzes in water to form a solution which issubstantially similar to an aqueous solution of cyauarnide in-analkalinesolution of an alkali metal or alkaline earth metal base. Ingen-. eral, we prefer to employ calcium cyanamide because of itsavailability, low cost, and high efficiency.

The reaction mixture containing the cellulosic material is maintained atthe desired reaction temperature for a sufficient length of time toobtain the desired degree of nitrogen substitution. Reaction occurs at asubstantial rate at reduced to ordinary temperatures. This is anadvantage where elevated temperatures are either unfeasible orundesirable. For more rapid reaction rates, the reaction temperature canbe increased. There is ordinarily n0 economic advantage in continuingthe reaction period beyond the point at which the desired or maximumdegree of substitution is achieved. In some cases, particularly atelevated temperatures, there may be some loss of substituted nitrogenwith prolonged treatment, although a cationic, nitrogenated product isstill obtained.

The cationic, nitrogenated cellulosic products can be separated from thealkaline reaction mixture, washed, dried, and employed as such. They canalso be acidified to form the cationic acid salts, which, in many cases,are preferred as, for example, where the cellulosic product is to bedyed with an acid dye salt.

The acid salt derivatives can be prepared from the washed and driednitrogenated products by treating them with an aqueous solution of thedesired acid. Ordinarily, they are most conveniently prepared byacidification of the alkaline reaction mixture with the particular acid,the derivative of which is desired. The pH ispreferably re-- duced to 4or less, in some cases, to as low at 1. Where operational expediencyrequires that the cyanamide reaction period be short, it may bedesirable to dry the treated cellulosic deriative, without Washing priorto acidification since this increases the nitrogen add-on.

Substantially any acid can be used, including inorganic and organicacids, such as hydrochloric, nitric, sulphuric, sulfurous, phosphoric,acetic, propionic acids, and the like. In general, we prefer to employhydrochloric acid.

The acidification treatment can be carried out at reduced, ambient orelevated temperatures, as, for example,

the temperature of the initial nitrogenation reaction. After the acidtreatment is completed, the nitrogenated cellulose product acid saltscan be removed from the reaction mixture, washed, and dried in anyconvenient manner.

The cationic, nitrogenated, cellulose derivatives possess the dyeingproperties of: wool and can readily be dyed with acid dyestufis such aslight green SF yellowish (CI. 670, Merck Index, 6th Edition, page 573),acid fuchsine (Cl. 692, trisodium salt of the trisulfonio acid of para--fuchsine), eosin Y (C.I. 768, disodium salt of 2,4,5,7- tctrabromo 9 Ocarboxyphenyl 6 hydroxy 3 isoxanthone), orange G (Cl. 27, disodium saltof l-phenylazo-2-naphthol-6,8-disulfonic acid), and the like.

The cationic cellulose deriatives are also substantive to anionictreating and coating compositions, such as anionic emulsions ofurea-formaldehyde, melamine-formaldehyde, polystyrene, acrylic resins,vinyl resins, rubber, rosin, and the like. Starch sizing is alsoimproved.

Paper furnish such as sulfate, soda, sulfite or groundwood pulp, can betreated with cyanarnide directly in the beater and, thereby, provides ahighly advantageous means for improving the retention of rosin andstarch size and other polymeric compositions added to impart suchproperties as wet strength and water resistance to the paper.

Cotton and viscose rayons can be treated in form of fiber, yarn or clothby immersion in the cyanamide reaction solution. Regenerated cellulosein sheet or film form, such as cellophane, can similarly be modified.The cellulose esters, such as cellulose acetate, can be treated ingranule, fiber, yarn, Woven cloth or film form.

EXAMPLE 1 Part I 90 grams of calcium cyanamide were slurried in 300this. of water for 15 minutes at 78 F. The solution was filtered, thefilter cake washed with 200 mls. of water, and the washings added to thefiltrate. The filtrate was acidified with cool 20% sulfuric acid to a pHof 5.0. The precipitated calcium sulfate was filtered ofi and washedwith 50 mls. of water, the washings being added to the solution ofcyanamide. The cyanamide solution was divided into 4 equal portionslabelled A, B, C, and D, into each of which was introduced 18 grams ofsliver cotton (Scientific Products 61453A). The pH of each test mix- 4and there was no appreciable substantivity to an acid dye.

Part II Reaction mixtures prepared similarly to A above were digested at32 F. for the indicated time intervals.

24 hrs. 48 hrs. 72 hrs.

N percent, D.B 0. 093 0.124 0.171

All 3 of these samples dyed well with Cl. 670, the color becomingprogressively deeper as the percent of nitrogen add-on increased.

EXAMPLE 2 Part I -3 strips of muslin fabric (25 gms./strip) wereimmersed and squeezed 6 times in solution of Ca(HNCN) containing 0.5mol/liter, and placed in a covered beaker at 78 F. for 4 hours. *100mls. of distilled water were added to each of the 3 strips, A, B and C.The pH of strip B Was adjusted to 7.0 and that of strip C to 3.7 withHCl. All 3 strips were then washed and dried. Portions of each of the 3strips were dyed with a 0.1% solution of Cl. 670, Washed and dried.

Control A B 0 N2 percent, D.B 0.02 0.09--- 0.10... 0.12. Dye resultsNone Light Light Deep green. green green.

This data demonstrates the improved take up of an acid dye salt by thecationic HCl salt of the nitrogenated cellulose fabric C as comparedwith that of the cationic nitrogenated parent derivatives, A and B PartII H 11.s gag N, 920m" 835 r g 6.0 5.0 3.7 20 Dye-mep Medium None NoneNone None N e een. green.

ture was adjusted as follows: 'Part III A to pH 11.6 with NaOH Strips ofmuslin were treated with solutions of 'B to pH 9.6 with NaOH c as is pH5.0 CMHNCN):

D t H 3,6 ith H01 at pH 11.8 at the temperatures and for the timeintervals All samples were maintained at 78 for 24 hours, at which timethe pH of each was reduced to 2.0 with HCl and the samples filteredand'washed. A portion of each sample was treated with an acid dye, LightGreen SF yellowish (Cl. 670) to determine cationicity and substantivity,washed and dried.

It will be noted that nitrogen add-on when the cyanamide digestion wascarried out at acid pH was negligible set out below, with the pHsubsequently adjusted to 3.7 with HCl, using the procedure described inPart II, and

grns. of desized muslin fabric were immersed in 400 mls. of an aqueousextract containing 0.525 mole of calcium cyanamide for 16 hrs. at 78 F.The pH was adjusted to 2.0 with HCl and the fabric washed, dried anddyed with Cl. 670. The percent N of the untreated control was 0.02%andthat of the cyanamide treated sample 0.45%. The control did not dyewhereas the treated fabric dyed a deep, uniform green.

EXAMPLE 4 Part I 90 gms. of sulfite pulp were slurried in 500 mls. ofwater which was divided into 5 equal parts. pH of the slurry was 5.2. 90gms. of hydrated grade calcium cyanamide were slurried in 300 mls. ofwater for 15 min. at 78 -F. and filtered. The filter cake was washedwith 200 mls. of water and the washings added to the filtrate. Thecalcium cyanamide extract was divided into 5 equal portions labelled A,B, C, D and E. A was added to one of the sulfite pulp portions withoutadjustment of the 11.3 pH. The pH of B, C, D and E was adjusted with HClto 9.6, 7.0, 3.7 and 2.0 respectively and the sulfite portions added.After 24 hrs. at 78 F., all samples were taken to pH 2.0 with HCl,filtered, washed and dried.

Substantial reaction in this case occurred only at a pH above 10. A dyeda deep green with Cl. 670, B dyed slightly and the others not at all.

Part II Runs similar to I-A were repeated except that diges- 6 Part IIRuns similar to I-A were made at difierent temperatures and fordifferent time intervals.

(3) did not dye.

EXAMPLE 6 The following pulps were obtained from the beater of a papermill and partially dewatered.

a medium green.

Oak Kraft Straw Waste Chip Paper O.D. solids, percent 37.G

Ash percent, D.B Nitrogen percent, D.B- Color 18 gms. D.B. (dry basis)of each of the pulps were diluted with 1000 mls. of water. 12 gms. CaNCNwere added to the straw pulp and the waste paper pulp. The extractobtained by digesting 12 gms. CaNCN in 200 mls. of water plus 125 mls.of water used to wash the filter cake was employed with the oak chippulp and the kraft pulp.

Product Oak Chip Kraft Straw Waste Temperature 78 F 78 F 200 F..." 78 FF 78 F. Time 5Mi11 24 hrs M 48 hrs 5 A lin..- 5 Min. Peagcelt N2, 0.227.278 0.097 .149 0.240 0.144. Dye, 3.1. 670 Medium Medium Light Deep DeepDeep green green green green green green.

tions were carried out at the temperatures and time EXAMPLE 7 periodsset out below.

s in. 1 l 1 r. 20 iiis. 24 iirs. 48 1 1 rs. 72 ii rs.

Percent N1, D.B--- 0.154 0.105 0.039 0.073 0.077 0.080

(1) and (5) dyed a medium light green. (2), (4)

and 6) dyed lightly. (3) did not dye.

EXAMPLE 5 Part I Pulp A B I C D E pH after 24 hr 11. 7 10. 9 7. 2 3. 92. 1 Percent N2, D.B- 0. 000 0. 145 0. 149 0. 054 0. 002 0. 001

A and B dyed a medium light green, the others not at all.

The cellulose nitrate coating was peeled from a sheet of cellophane byimmersing in water for 10 min. at 120 F. 10 gms. of the viscose sheetwere immersed in 460 mls. of a solution containing 0.704 mole of calciumcyanamide. After 16 hrs. at 78 F., the pH was adjusted to 2.0 with HCl.The treated film was washed and a portion dyed by immersion in 0.01% CI.670. The film dyed a deep, clear green. A portion of the untreated sheetdid not dye at all.

EXAMPLE 8 The cellulose nitrate coating was removed from 9 sheets ofcellophane and the 10 gm. sheets were labelled A, B, C, D, E, F, G, Hand I. 200 gms. CaNCN were slurried in 1 liter of water at 100 F. andfiltered. The filtrate, 946 mls., pH 10.9, contained 1.47 moles of thecyanamide.

Sheet F was immersed for 5 min. in 50 mls. of the cyanamide filtratewhich had been adjusted to pH 3.0 with HCl, removed and dried at 78 F.Sheet I was similarly processed except that the pH of the cyanamidesolution had been adjusted to 7.0. Both F and I were then immersed in anaqueous HCl solution, pH 2, washed, and dried at 78 F.

The other 7 sheets were immersed in 846 mls. of the solution at 78 F.containing 1.305 moles of the cyanamide. After 5 minutes sheets A, B, C,D, E were removed -from the bath. Sheet A was immediately plunged into abath of distilled water adjusted to pH 2.0 with HCl. After 1 hour, thesheet was washed and dried at 78 F. Sheet B was dried at 200 F. to anoven dry solids content of approximately and processed as in A. Sheet Cwas dried to an OD. solids content of 95 at 78 F. and processed as in A.Sheet D was dried to an OD. solids content of 95% at 32.5 F., andprocessed as in A. Sheet E was dried to an OD. solids content of 95% at78 F washed without pH adjustment, then dried at 78 F. to D. solidscontent of 95%. Sheets G and H were allowed to soak 4 hours in thecyanamide solution at the 10.9 pH, then removed, sheet G was dried at200 F. to an OD. solids content of 95% and sheet H at 78 F. to an OD.solids content of 95%. Then, both sheets were processed as in A.

A small portion of each sheet was immersed in 0.01% concentration of theacid dye Light Green SF, yellowish Cl. 670, then washed in distilledwater and air dried.

EXAMPLE 11 100 gms. of sulfite pulp were mixed with 18% NaOH and allowedto stand for 1 hr. at 73 F. The caustic was then poured off and the pulppressed to a weight of 300 gms. The press cake was shredded and allowedto age for 65 hrs. in a sealed jar at 73 F. 32 g-ms. CS were added toform the xanthate and the mixture shaken for Blank A B O D E F G H IPercent N7, D.B 0.009 0.100 0.607--" 0.587---- 0.292---- 0.607 0.080 0.690 0.940--.- 0.088 Dye None None deep deep deep None None deep deepNone green. green. green. green. green.

Sheets A and C were similarly processed except that C was dried afterimmersion of the cyanamide solution prior to acidification. The resultsindicate that the short 5 minute eyanamide treatment can be adequate ifthe solution is dried on the cellulose prior to formation of the acidsalt.

Sheet E, though cationic, as indicated by other tests, was not in theform of the acid salt and, therefore, did not react with the acid dyesalt.

Sheets F and I were processed like C except for treatment with acid andneutral cyanamide solutions respectively. Nitrogen add-on was negligibleand the sheets with 500 mls. of water. pH of themixtures was 10.4. Aftertreatment at the temperatures and for the times indicated, the pH wasreduced to 2.0 with HCl. The treated cellulose acetate was thenfiltered, washed and 3 hrs. at 78 F. The material was divided into 2equal portions.

84.5 gms. 18% NaOH and 382 mls. water were added to portion A andstirred for 2 hrs.

25 gms. CaNCN were slurried in 500 mls. water for 30 min. at 78 F. 21gms. Na CO were added. The mixture was stirred for 5 min. and filtered.'Ihe filtrate, 470 mls., was added to portion B and the mixture stirredfor 2 hrs. A and B were stored at 73 F. for 16 hrs.

200 mls. of A and B were each poured into 200 mls. of water containing50 mls. glacial acetic acid. The nitrogenated, regenerated celluloseacid salt was filtered, washed were not cationic. I and dried- EXAMPLE 918 gms. of cellulose acetate powder (Du Pont WA A B 526-XP, percentacetyl 38.49, B8. 2.32) slurried in 100 mls. or water were ded to 100 mlf a solution p yfij o .ift'ii'ii:::::::::::::::::::::::::: 3'23. 3335green. of calcium cyanamide prepared by extracting 90 gms. 40

Although this invention has been described with reference toillustrative embodiments thereof, it will be apparcut to those skilledin the art that the principles of this invention can be embodied inother forms but within the dried. scope of the claims.

200 F. 32. 5 F. Blank 78 F. 24 hrs.

5 min. 1 hr. 24 hr. 48 hr.

Peficefilt N 2, 0. 000 0. 07 7 0. 072 0. 083 0. 095 0.098. Dye, (5.1.670. None medium medium medium 7 medium medium green. green. green.green. green.

The acetyl content of a sample treated at 325 F. for We claim:

72 hours, nitrogen add-on 0.177%, was 29.00%, indicating a substantialdegree of hydrolysis.

EXAMPLE 10 A similar procedure was employed as in Example 9, except thatthe cellulose acetate powder used was Du Pont Z.a55835p, percent acetyl40.42, D.S. 2.52.

1. A process :for making a cationic nitrogenated cellulose product whichcomprises reacting a cellulosic material selected drom the groupconsisting of cellulose, fatty acid esters of cellulose, and cellulosexanthate with an aqueous alkaline solution of cyana-mide.

2. A process for making a cationic nitrogenated cellulose product whichcomprises reacting a cellulosic m-a- T he acetyl content of a sampletreated at 32.5 F. for 72 hours, nitrogen add on 0.09%, was 29.80%,indicating a substantial degree of hydrolysis.

ter ial selected from the group consisting of cellulose, fatty acidesters of cellulose, and cellulose xanthate with an 75 aqueous alkalinesolution of a metal salt of cyanamide,

9 the metal being selected from the group consisting of alkali andalkaline earth metals.

3. The process of claim 2 in which the metal cyanamide salt is calciumcyanamide.

4. A process for making a cationic nitrogenated cellulose product whichcomprises reacting a cellulosic material selected from the groupconsisting of cellulose, fatty acid esters of cellulose, and cellulosexanthate with an aqueous alkaline solution of cyanamide and thenacidifying the reaction mixture.

5. A process for making a cationic nitrogenated cellulose product whichcomprises reacting a cellulosic material selected from the groupconsisting of cellulose, fatty acid esters of cellulose, and cellulosexanthate with an aqueous alkaline solution of a metal salt of cyanamide,the metal being selected from the group consisting of alkali andalkaline earth metals, and then acidifying the reaction mixture.

6. The process of claim 5 in which the metal cyanamide salt is calciumcyanamide.

7. The process of claim 4 in which the acid is hydrochloric acid.

8. The process of claim 4 in which the cellulosic material is separatedfrom the cyanamide solution and dried without washing prior toacidification.

9. The process of claim 4 in which the cellulosic material is cotton.

10. The process of claim 4 in which the cellulosic material is paperpulp.

11. The process of claim 4 in which the cellulosic material isregenerated cellulose.

12. The process of claim 4 in which thecellulosic ma.- terial iscellulose acetate.

13. The process of claim 9 in which the aqueous alkaline solution ofcyanarnide is prepared by dissolving calcium cyanamide in water.

14. The process of claim 10 in which the aqueous alkaline solution ofcyanamide is prepared 'by dissolving calcium cyanamide in water.

15. The process of claim 11 in which the aqueous alkaline solution ofcyanamide is prepared by dissolving cyanamide in water.

16. The process of claim 12 in which the aqueous alkaline solution ofcyanamide is prepared [by dissolving calcium cyanamide in water.

17. The cationic, nitrogenated reaction product of a cellulosicmaterial, selected from the group consisting of cellulose, the fattyacid esters of cellulose, and cellulose xanthate and an aqueous alkalinesolution of cyanamide.

18. The acid salt produced by acidification of the reaction product ofclaim 17.

19. The product of claim 18 in which the cellulosic material is cotton.

20. The product of claim 18 in which the cellulosic material is paperpulp.

21. The product of claim 18 in which the cellulosic material isregenerated cellulose.

22. The product of claim 18 in which the cellulosic material iscellulose acetate.

23. The product of claim 18 in which the acid salt is the hydrochloride.

References Cited in the file of this patent UNITED STATES PATENTS2,015,104 Dreyiiuss Sept. 24, 1935 2,332,649 Bock et al Oct. 19, 19432,338,681 Bock et a1. Ian. 4, 1944 2,339,739 Blackshaw et a1 Jan. 18,1944 2,446,682 Whitner Aug. 10, 1948 2,538,903 Gaver et a1 Jan. 23, 19512,894,944 Paschall July 14, 1959 FOREIGN PATENTS 508,977 Canada Ian. 11,1955 UNITED STATES PATENT oTTTcE CERTEHCATE 0F QGRREE'HON Patent No,3,051,698 August 28, 1962 Lee H. Elizer et al., It is hereby certifiedthat error appeafs iri the above numbered patent requiring correctionand that the said Letters Patent should read as corrected below.

Column 5, line 58, for "Example 5" read Example 4 Signed and sealed this5th day of February 19630 (SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

1. A PROCESS FOR MAKING A CATIONIC NITROGENATED CELLULOSE PRODUCT WHICHCOMPRISES REACTING A CELLULOSIC MATERIAL SELECTED FROM THE GROUPCONSISTING OF CELLULOSE, FATTY ACID ESTERS OF CELLULOSE, AND CELLULOSEXANTHATE WITH AN AQUEOUS ALKALINE SOLUTION OF CYANAMIDE.
 17. THECATIONIC, NITROGENATED REACTION PRODUCT OF A CELLULOSIC MATERIALSELECTED FROM THE GROUP CONSISTING OF CELLULOSE, THE FATTY ACID ESTERSOF CELLULOSE, AND CELLULOSE XANTHATE AND AN AQUEOUS ALKALINE SOLUTION OFCYANAMIDE.